Sensors and sensor arrays with reduced size and power, and enhanced sensitivity, selectivity, speed, stability and reliability are required for detection of chemical and biological species especially in space exploration and homeland security applications. Carbon nanotubes, solid state semiconductor nanowires, and organic molecular wires provide bottom-up interfaces for molecular moieties to be discriminated as inputs and electronics as outputs for ideal molecular electronic sensing applications. At NASA Ames, we have been dedicated to development of hierarchical nanosensor array platforms based on these one-dimensional nanostructures. Multiwall carbon nanotube nanoelectrode arrays were interfaced with DNA probes for label-free detection of ~1000 oligo and genomic DNA molecules. Single wall carbon nanotubes were used to form networks cross interdigital electrode arrays for ppm and ppb level detection of toxic and explosive species such as methane, carbon oxides, ammonia, nitric oxides, and vapor of organic compounds such as benzene, acetone, and nitro-toluene. In addition to substantially increased sensitivity and decreased size and power consumption, our nanosensors show manufacturability with >90% device yield at wafer scale, >90% reproducibility in terms of sensitivity results from devices to devices and from time to time, and enhanced signal to noise ratio.